Hydraulic reciprocating system



May 25, 1965 Filed April l5, 1963 D. E. LIGON HYDRAULIC RECIPROCATINGSYSTEM 2 Sheets-Sheet 1 a; T-'5:5 256 7.1- I@ INVENTOR May 25, 1965 D.E. LlGoN HYDRAULIC RECIPROCATING SYSTEM 2 Sheets-Sheet 2 Filed April 15,1963 1 Cm ..l I

frage/ffm United States Patent O 3,185,040 HYDRAULIC RECIPROCATINGSYSTEM D. Elmon Ligon, Denver, Colo., assigner to American Brake ShoeCompany, New York, NX., a corporation of Delaware Filed Apr. 15, 1963,Ser. No. 273,090 Ciaims. (Cl. 91-277) This invention relates tohydraulic self-reciprocating systems and more particularly to a systemwhich is operable to reciprocate a hydraulic piston automatically andWithout the customary manual or electrical control at the end of eachstroke.

It has been an objective of this invention to provide a hydrauliclinearly reciprocating motor or pump having hydraulic control meansbuilt in-to the reciprocated member such that when the reciprocatedmember reaches the end of a stroke the system will automatically causethe member to move linearly in the opposite direction, without theassistance of conventional manual or electrically controlled valves. Tothis end this invention incorporates uid passageways into thereciprocated piston operable to selectively actuate a pilot valve at theend of each stroke. The pilot valve in turn controls a main ow controlvalve which causes reversal of .the direction of the fluid flow to andfrom the main piston. With this arrangement the piston continues toautomatically reciprocate so long as pressure is maintained to thesystem.

Another objective of this invention has been to provide an inexpensivehydraulic reciprocating system having a minimum number of parts subjectto wear or breakdown. Continuous operating time for a reciprocatingpiston in accordance with this invention may be measured in terms ofthousands of running hours even at relatively high speeds under adverseconditions. For example, this system has found one application as arugged, heavy duty motor for compacting wet concrete. Advantageousutilization of the invention for this purpose results from the fact thatthere are no mechanical linkages or components subject to wear, cloggingor breakage.

Another objective of this invention has been of provide a hydraulicreciprocating system displaying no dead spots in operation. A dead spotis a piston location at which maximum power cannot be supplied to 4thereciprocating piston. In many systems .this phenomenon occurs at thebeginning of a stroke where back pressure on the piston may cause thecontrol valve to lock in some intermediate position at which there is nofluid ow or very little flow to either side of the main piston. Toeliminate dead spots this invention incorporates a pilot valve into thesystem operable to control movement of the main control valve.

Yet another objective of this invention has been to provide anadjustable stroke reciprocating motor which has no manual orelectrically controlled valve to determine the length of the pistonstroke. Thus, this motor is particularly adapted for use in heavy dutyinstallations where breakdown is intolerable or where the motor issubject to extended running time.

These and other objectives and advantages of this invention will be morereadily apparent from a description of the drawings in which:

FIGURE l is a diagrammatic illustration of one embodiment of the motorand control system, partially in cross section, showing the controlvalves in the position for moving the main piston from right to left,

FIGURE 2 is a diagrammatic illustration similar to FIGURE l but showingthe control valves in the position for moving the main piston from leftto right,

FIGURE 3 is a diagrammatic illustration of a second embodiment of theinvention,

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FIGURE 4 is a cross sectional view of another embodiment of the motor inwhich the piston stroke is adjustable.

Referring to FIGURES 1 and 2, it will be seen that the reciprocatingsystem consists essentially of a reciprocating motor 1t), a pilot valve11 and a main control valve 12. The pilot valve 11 and main controlvalve 12 are used in the system to control flow of hydraulic uid underpressure to opposite ends of the piston 13 of the motor 10.

The reciprocating member or motor piston 13 is slidingly and sealinglymounted within a housing or cylinder 14 and has a piston rod 15 whichextends through a bearing block 16 at one end of the cylinder 14. Theopposite end of the cylinder 1d is enclosed by an end plate 17. Fluid issupplied to the opposite sides of the piston 13 through pressure ports20, 21 in the bearing block 16 and end plate 17 respectively.

A port block 22 is mounted on the end of the bearing block 16 and has acentral bore 23 co-axial with the bore 24 in the bearing block. An endcap 26 is mounted over the forward end of the port block 22 and also hasa central aperture 27 co-axial with and of the same size as the bores23, 24 in the port block and bearing block. The end plates 17, 26, thebearing block 16, and port lock 22 have a plurality of aligned aperturestherein which receive bolts 36 to hold the components of thereciprocating motor in assembled relationship.

The port block 22 has four pressure ports 31, 32, 33 and 34 extendingradially from the central bore 23. Two of the pressure ports 32, 33 arelocated in the same radial plane on opposite sides of the port block. Inthe same manner but spaced axially from the pressure ports 32, 33, thepressure ports 31, 34 are located on opposite sides of the port block inthe same radial plane. The ports 31, 32 are both connected to a pressuresource such as pump 3S by conduits 39, 4) and 41. Ports 33, 34 areconnected to ports 43, 44 of pilot valve 11 by means of conduits 4S, e6respectively such that pressures from ports 33, 34 is operable tocontrol movement of the piston 4S of pilot valve 11.

The port block also has four drain ports 50, 51, 52 and 53 locatedadjacent the pressure ports 31, 32, 33 and 34 respectively with two ofthe drain ports 50, 53 located in the same radial plane but on oppositesides of the port block and the other two drain ports 51, 52 similarlylocated on opposite sides of the port block and in the same radialplane. Two of the drain ports 50, 51 are connected to reservoir or tank55 by conduits 56, 57 respectively while the drain port 52 is connectedto conduit 46 by a conduit 53 and port 53 is connected to conduit 45 bya conduit 59.

In the forward position of the motorpiston 13, the pressure ports 32, 33and the drain ports 51, 52 are .adapted to be interconnected to form apair of fluid passages. To this end, the piston rod 15 has a pair ofannular grooves 60, 61 formed in its peripheral surface which in theforward position of the motor, becomes aligned with the pressure ports32, 33 and the drain ports 51, 52. In the rearward position of the motorpiston 13, the grooves are aligned with and interconnect the pressureports 31, 34 and the drain ports S0, 53.

The pilot valve 11 is a four-way hydraulic valve and consists of acylinder 62 within which the piston 48 is slidable to either of twopositions in an axial bore 63. The central bore 63 is open at one end topiston port 43 and at the opposite end to piston port 44. Equally spacedalong the central bore 63 are iive annular grooves 64, 65, 66, 67 and 68which serve as fluid passageways. The central groove 6e is connected toa pressure intake port (shown in dotted lines) 74B which is connected topump er 38 by conduits 71, 72. The two adjacent passageways or annulargrooves 65, 67 are connected to pressure ports 73, 74 respectively.Ports 73, 74 are in turn connected to ports 75, 76 of the main controlvalve 12 by conduits 7'7 and 78 respectively in such a manner thatpressure from these ports is operable to control the main control valve12. The outermost annular grooves 64, 68 are connected to the reservoirtank`55 by passageways 81, 82 and drain port 80 in the pilot valvecylinder 62.

The piston 48 of pilot valve 11 has a pair of axially spaced grooves 85,86 located therein and adapted in one position to connect passageways67, 68 and passageways 65, 66 and in the other position to connectpassageways 66, 67 and passageways 64, 65. The purpose of thisinterconnection of passageways will be more fully explained hereinafterin connection with the operation of the system.

Main control valve 12 is a four-way valve structurally similar to pilotvalve 11. It` consists of a cylinder 90 within which apiston 91 isslidable in an axial bore 92 to either of two positions. The centralbore 92 is connected at one end to port 75 and at the opposite end toport 76. Equally spaced along the central bore 92 are ve annular groovesor fluid passageways 93, 94, 95, 96 and 97. The central groove 95 isconnected to a pressure intake port (shown in dotted lines) 98 which isconnected by conduits 99 and 72 to the pump 38. The two adjacentpassageways or annular grooves 94, 96 are connected to pressure ports100, 101 respectively. Ports 100, 101 are in turn connected to ports 20,21 of the motor 10 by conduits 102 and 103 respectively so that pressurefrom these ports is operable to control reciprocation of piston 13. Theoutermost annular grooves 93, 97 are connected to drain port 104 bymeans of passageway 105 in the main control valve cylinder 90.

The piston 91 of main control valve 12 has a pair of axially spacedgrooves 106, 107 located therein and adapted in one position to connectpassageways 96, 97 and passageways 94 and 95 and in the other positionto connect passageways 95 and 96 and passageways 93v and 94. The purposeof this interconnection of passageways will be more fully explainedhereinafter in connection with the operation of the system.

Referring to FIGURE 1, the pilot valve 11 and the main control valve 12are shown in the position for moving the piston 13 from right to left,or forwardly. With the piston moving in this direction fluid pressure issupplied from the .pump 38 via conduit 72, 71 to the pilot valve 11 andthrough the pilot valve via passageway 66, groove 86, passageway 65 andconduit 77 to the port 75 of the main control valve 12. The pressure inport 75 causes the piston 91 of the main control valve to move to theleft and to remain in that position so long as the motor piston 13 ismoving forward. Fluid pressure is supplied to the port 21 of the motor10 from the pump 38 Via conduits 72 and 99 to the pressure inlet port 98and via passageway 95, groove 107, passageway 94 vthrough conduit 103 tothe port 21. Fluid is exhausted at this time from the forward side ofpiston 13 via port 20, conduit 102, passageway 96, groove 106 andpassageways 97, 105 to drain port 104 from whence it is conducted to thereservoir or tank 55.

When the piston 13 arrives at its forward limit of movement, the grooves60, 61 in the piston rod 15 become aligned with the ports 32V, 33 and51, 52 respectively. Upon alignment of the piston rod groove 60 with thepressure ports 32, 33 fluid pressure is supplied to the left end ofpilot valve piston 48 so as to cause it to move to the right. Thismovement results from fluid pressure being supplied from pump 38 viaconduits 39,141, groove 60 and conduit 45 to the valve piston port 43.Sirnultaneously uid is exhausted from the right side of the piston 48via conduits 46, 58, drain port 52, groove 61, drain ports 51 andconduitV 57 to the tank 55. With the pilot valve piston 48 in theposition illustrated in FIGURE 2,

uid pressure is supplied tothe left end of the control valve piston 91so as to cause the piston to move toward the right. This pressure issupplied from pump 38 by conduits 72, 71, passageway 66, groove andconduit 78 to the main control valve piston port 76. At this time uid isexhausted from the right side of piston 91 via conduit 77, passageway65, groove 86, passageways 64 and 82 to the tank 55. Thus the locationof the'motor piston 13 at itsforward limit of movement causesrepositioning of the pistons 48 and 91 of the pilot valve 11 and maincontrol valve 12 so as to start the motor moving in the rearwarddirection.

With the main control valve 12'located in the FIG- URE 2 position, uidpressure is supplied to the forward side of motor piston 13 andexhausted from the rear side. The pressure to the forward side of thepiston 13 is supplied from the pump 38 via conduits 72 and 99,passageway 95, groove 106, passageway 96, and conduit 102 to the motorport 20. Simultaneously fluid is drained from the rear side of thepiston via conduit 103, passageway 94, groove 107, passageways 93, 105to the drain port 104 and hence to storage tank 55. At this time thepiston 13 moves rapidly to the right or rearwardly because theyeifective area against which the pressure reacts is smaller than thearea 111 against which the uid acts to move the piston in the forwarddirection. Otherwise expressed, the forward fluid chamber 112 is of muchless volume than the chamber 113 and therefore requires less iiuid flowto cause the same amount of linear movementof the piston in the rearwarddirection than in the forward direction. Thus the piston moves rapidlyto the right and slowly in the forward direction to the left. However,in moving to the left at the slower rate of speed, the piston has a muchgreater mechanical advantage as a result of the greater piston area, andthus is able to apply a much greater force on a load than that which itis capable of applying in a rearward direction. In those applications inwhich it is desirable to move the piston at the same rate of speed inboth the forward and rearward directions, the piston rod 15 maybeextended rearwardly from the rear surface 111 of the piston through theend plate 17, so that the etfective area against which the fluidpressure reacts in moving the piston in both the forward and rearwarddirection will be equal.

When the piston 13 has moved all the way to the right or to the rearwardlimit of its movement, the piston rod grooves 60, 61 :become alignedwith the ports 50, 53 and the ports 31, 34 respectively. The pilot valve11 and the main control valve 12 are then moved into their firstposition as illustrated in FIGURE 1 so as to cause movement of thepiston from right to left or in the forward direction. At this timepressure is supplied from the pump 38 via conduits 39 and 40, port 31,groove 61, port 34, and conduit 46, to `the right end of piston 48.Simultaneously fluid is exhausted from the left end of piston 48 so asto permit the piston to move to the leftv or into its first position.The fluid is drained through portl 43, conduits 45, 59, drain port 53,groove 60, drain port 50' and conduit 56 to the tank 55.v

When the pilot valve is actuated or moved into its rst position itcauses the main control valve to also be moved into the rst position.This occurs as a result of fluid pressure being supplied from the pump38 via conduits 72,V 71, passageway 66, groove S6, passageway 65 andconduit 77 to the main control valve piston port 75.

Simultaneously uid is exhaustedl from the control valve port 76 viaconduit 78, passageway 67, groove 85, passage- Ways 68, 81 to the drainport 80 and thus to the tank 55.

With both the pilot valve 11 and the main control valve 12 located intheir first positions, the motor piston 13 again moves from right toleft or rearwardly. Fluid at this time is supplied to the rear of piston13 from pump 38 via conduits 72, 99, passageway 95, groove 107,passageway 94 and conduit 103. Simultaneously fluid is exhausted fromthe forward side of piston 13 via conduit 102, passageway 96, groove 106and passageways 97, 105 to the drain port 104.

As should now be obvious, the hydraulic reciprocating system of FIGURESl and 2 is operable to reciprocate the motor piston 13 continuously orautomatically without the assistance of any manual or electronic controlvalves, so long as pressure is supplied from the motor 38 to the variouspressure inlet ports.

Referring to FIGURE 3, there is shown a second embodiment of theinvention. In this embodiment, similar numerals followed 'by the suiiixa are used to designate parts which are identical to those of FIGURE 1.

The principal difference between the embodiment of FIGURE 3 and thatillustrated in FIGURE 1 resides in the fact that the piston rod 120extends axially from both ends of the piston 121 through port blocks 122and 123 mounted on both ends of the cylinder 124. The port blocks 122,123 each have a pair of radially aligned pressure ports 127, 128 and apair of radially aligned drain ports 129, 130.

At each end or on both sides of the piston 121, the piston rod 120 has apair of spaced annular grooves 132, 133. The grooves 132, 133 areaxially spaced apart the same distance as that between the pressureports 127 and the drain ports 129.

The pressure ports 127 and 128 and the drain ports 129, 130 areconnected to the pump 38a, the pilot valve 11a and the main controlvalve 12a in the identical manner as disclosed relative to the FIGURE 1modification. Thus, the piston 121 continues to reciprocate and changeits direction of linear motion at each end of its stroke so long aspressure is supplied from the pump to the motor. At each end of thestroke, the pressure ports 127 and 12S are interconnected by the annulargroove 132 and the drain ports 129 and 130 are interconnected by theannular groove 133. The primary advantage of the FIGURE 3 modiicationover that of FIGURE 1 resides in the fact that the piston and piston rodof this modification are balanced so that there is no tendency for thepiston 121 to skew relative to the cylinder 124. Thus wear between theseparts is minimized, since a port block is located at each end of thecylinder 124 and each block acts as a guide to maintain alignmentbetween the cylinder and piston.

Referring to FIGURE 4, there is shown another modification of the systemin which the stroke of the piston is adjustable. In this modificationelements which are similar to the modiiication of FIGURE l aredesignated by identical numbers followed by the suflix b.

While the pilot valve and main control valve have not been illustratedin this modification, Vit should be understood that these parts areidentical to the FIGURE l modiication and are connected in the samemanner.

In this modification, the piston rod 140 is made from two relativelyadjustable sections 141 and 142. Each section has a pair of peripheralannular grooves 143, 144 and 145, 146 respectively which are spacedapart the same distance as that between the drain ports and the pressureports. By adjusting the relative positions of the sections 141, 142, thedistance between the two pairs of grooves 143, 144 and 145, 146 may bealtered.

For purposes of adjusting the distance between the pairs of grooves, thepiston rod section 141 has a threaded end portion 150 which is of lessdiameter than that of the piston rod 141. The other piston rod section142 is threaded onto the threaded portion 150 of the member 141 so as tobe adjustable thereon. A lock nut 151 is also threaded on the end of thethreaded section 150 to lock the member 142 in any adjusted position.

At one end of the piston stroke, the grooves 143 and 144 interconnectthe drain ports 50b and 53b and the pressure ports 31b and 341:respectively. At the opposite end of the stroke, the groove 145interconnects theV pressure ports 32b and 33b and the groove 146interconnects the drain ports 51b and 52b. By adjusting the pair ofgrooves 145, 146 to a position closer to the 6 grooves 143, 144, thestroke of the piston may be lengthened and by moving the pair of groovesfurther apart, the stroke may be appreciably shortened. Thus, theadjustment between the grooves provides an infinite number of pistonstroke adjustments.

Having described my invention, I claim:

l. A variable stroke hydraulic reciprocating system comprising,

a hydraulic cylinder,

slidable means including a piston and piston rod mounted within saidcylinder,

a plurality of ports associated with said cylinder,

valve means operable to control uid flow to opposite ends of saidpiston,

said slidable means having a plurality of fluid passageways operable toselectively connect said ports to said valve means and thereby controlsaid valve means, and

means for varying the spacing between said ports and said passageways toalter the length of the stroke of said piston Within said cylinder.

2. A hydraulic reciprocating system comprising,

a hydraulic cylinder,

a piston having a piston rod extending through one end w-all of saidcylinder,

a port block attached to one end wall of said cylinder,

said piston rod extending into said port block,

valve means operable to control fluid flow to opposite ends of saidpiston,

said piston rod having a plurality of uid passageways operable toselectively connect ports in said port block to said valve means andthereby control said valve means, and

means for adjusting the distance between said ports and said iuidpassageways to vary the stroke of said piston within said cylinder.

3. A fluid energy translating device comprising,

a hydraulic cylinder,

a piston mounted within said cylinder and having a piston rod extendingthrough one end wall of said cylinder,

a port block attached to one end wall yof said cylinder,

said piston rod extending into said port block,

said port block having a plurality of connectable ports therein,

said piston rod having a plurality of fluid passageways operable toselectively interconnect ports in said port block, and

means for adjusting the distance between said ports and said fluidpassageways to vary the stroke of said piston Within said cylinder.

4. A iiuid energy translating device comprising,

a hydraulic cylinder,

a piston mounted within said cylinder and having a piston rod extendingthrough one end wall of said cylinder,

a port block attached to one end Wall of said cylinder,

.said piston rod extending into said port block,

said port block having a plurality of connectable ports therein,

said piston rod having a plurality of axially spaced iiuid passagewaysoperable to selectively interconnect ports 1n said port block, and

means for adjusting the distance between said fluid passageways to varythe stroke of said piston within said cylinder.

5. A uid energy translating device comprising,

a hydraulic cylinder,

a piston mounted within said cylinder and having .a piston rod extendingthrough one end wall of said cylinder,

a port block attached to one end wall of said cylinder,

said piston rod extending into said port block and having two relativelyaxially adjustable sections located within said port block,

said port block having a plurality of connectable ports therein,

each of saidpiston rod sections having a plurality of fluid passagewaysoperable to selectively interconnect ports in said port block, and

threaded means betweeny said sections for varying the relative positionsof said sections to alter the spacing between said fiuid passageways andthereby vary the stroke of said piston Within said cylinder.

References Cited by the Examiner UNITED STATES PATENTS 720,263 2/03Lepley 91-2'77 Ernst 91-308 Morgan 91-277 Holm 9 1-461 Schemmel 91-297Ellis `91-314 Paris 91-317 Coberly 91-308- FOREIGN PATENTS GreatBritain. Switzerland.

FRED E. ENGELTHALER, Primary Examiner.

7/ 10 Jenner 91-308 15 SAMUEL LEVINE, Examiner.

1. A VARIABLE STROKE HYDRAULIC RECIPROCATING SYSTEM COMPRISING, AHYDRAULIC CYLINDER, SLIDABLE MEANS INCLUDING A PISTON AND PISTON RODMOUNTED WITHIN SAID CYLINDER, A PLURALITY OF PORTS ASSOCIATED WITH SAIDCYLINDER, VALVE MEANS OPERABLE TO CONTROL FLUID FLOW TO OPPOSITE ENDS OFSAID PISTON, SAID SLIDABLE MEANS HAVING A PLURALITY OF FLUID PASSAGEWAYSOPERABLE TO SELECTIVELY CONNECTED SAID PORTS TO SAID VALVE MEANS ANDTHEREBY CONTROL SAID VALVE MEANS, AND MEANS FOR VARYING THE SPACINGBETWEEN SAID PORTS AND SAID PASSAGEWAYS TO ALTER THE LENGTH OF THESTROKE OF SAID PISTON WITHIN SAID CYLINDER.